1. Field of the Invention
The present invention relates to an apparatus that forms a pattern.
2. Discussion of the Related Art
Recently, various flat panel displays that reduce weight and volume of a cathode ray tube have been developed. Examples of the flat panel displays include a liquid crystal display (LCD) device, a field emission display (FED), a plasma display panel (PDP), and a light emitting display (LED).
The LCD device displays images by controlling light transmittance of liquid crystal with an electric field. The LCD device includes an LCD panel having a plurality of liquid crystal cells arranged in a matrix type, and a driving circuit for driving the LCD panel.
The LCD panel is comprised of a plurality of pixel electrodes and a common electrode, wherein the plurality of pixel electrodes apply an electric field to the respective liquid crystal cells. The pixel electrodes are formed in the respective liquid crystal cells on a lower substrate, and the common electrode is formed on an entire surface of an upper substrate. The pixel electrodes are respectively connected with a plurality of thin film transistors TFTs used as switching elements. The pixel electrodes and the common electrode drive the liquid crystal cells in response to data signals supplied through the TFTs.
FIG. 1 is a cross sectional view of a general LCD panel. As shown in FIG. 1, the general LCD panel includes a color filter array substrate 4, a TFT array substrate 2, and a liquid crystal layer 52. The color filter array substrate 4 is comprised of a black matrix layer 44, a color filter layer 46, an overcoat layer 47, a common electrode 48 and an upper alignment layer 50a which are sequentially formed on an upper substrate 42. The TFT array substrate 2 is comprised of a TFT, a pixel electrode 22 and a lower alignment layer 50b which are sequentially formed on a lower substrate 1. The liquid crystal 52 is formed in a space between the color filter array substrate 4 and the TFT array substrate 2.
The TFT of the TFT array substrate 2 is comprised of a gate electrode 6 connected with a gate line, a source electrode 8 connected with a data line, and a drain electrode 10 connected with the pixel electrode 22 by a drain contact hole 26. In addition, the TFT includes semiconductor layers 14 and 16 for forming a charged channel between the source electrode 8 and the drain electrode 10 by a gate voltage supplied to the gate electrode 6. The TFT selectively supplies a data signal of the data line to the pixel electrode 22 in response to a gate signal of the gate line.
The pixel electrode 22 is positioned in a pixel region defined by the gate and data lines. The pixel electrode 22 is formed of a transparent conductive material having a high light transmittance. The pixel electrode 22 is formed on a passivation layer 18 coated on an entire surface of the lower substrate 1, and the pixel electrode 22 is electrically connected with the drain electrode 10 by the drain contact hole 26 passing through the passivation layer 18. A potential difference is generated between the pixel electrode 22 of the lower substrate 1 and the common electrode 48 of the upper substrate 42 by the data signal supplied through the TFT. For example, the liquid crystal 52 having dielectric anisotropy is twisted by the potential difference generated between the pixel electrode 22 and the common electrode 48. As a light source emits light, the amount of light transmitted toward the upper substrate 42 through the pixel electrode 22 is controlled by the twisted liquid crystal 52.
The black matrix layer 44 of the color filter array substrate 4 is formed corresponding to the TFT and the gate and data lines of the lower substrate 1. The black matrix layer 44 divides the pixel regions for the color filter layer 46. The black matrix layer 44 prevents light leakage and improves contrast ratio.
The color filter layer 46 is formed corresponding to the pixel regions divided by the black matrix layer 44. The color filter layer 46 is formed of red(R), green(G) and blue(B) filters, so as to express red, green and blue colors.
The overcoat layer 47 is formed on the upper substrate 42 having the color filter layer 46. The overcoat layer 47 is formed by coating a transparent resin having the insulating characteristics on the upper substrate 42. The overcoat layer 47 is provided for an electric insulation between the black matrix layer 44 and the common electrode 48. In the case of a TN mode LCD device, it is unnecessary to provide the overcoat layer 47.
A common voltage is applied to the common electrode 48, wherein the common voltage serves as a reference voltage for driving the liquid crystal. As explained above, the common electrode 48 and the pixel electrode 22 generate the potential difference. In the case of an IPS mode LCD device, the common electrode is formed on the lower substrate 1.
The upper and lower alignment layers 50a and 50b used for alignment of the liquid crystal are respectively formed on the color filter array substrate 4 and the TFT array substrate 2. The upper and lower alignment layers 50a and 50b are formed in steps of coating an alignment material such as polyimide PI, and rubbing the coated alignment material.
The liquid crystal 52 is formed in the space provided between the color filter array substrate 4 and the TFT array substrate by ball spacers and column spacers.
The above-mentioned various elements of the LCD panel are formed by repeated processes. A photolithography is generally used to pattern the various elements of the LCD panel.
To perform photolithography, a patterning material layer is formed on the substrate, and a mask of a predetermined pattern is positioned above the pattern material layer. In this state, light is applied to the entire surface of the substrate, thereby forming a desired pattern.
However, the photolithography has a disadvantage of high manufacturing cost since the photolithography necessarily uses the mask of the predetermined pattern. Since the photolithography requires a development process, it complicates the process and increases process time.
To overcome the problems of photolithography, a patterning apparatus using a printing roller has been proposed.
FIG. 2 is a schematic view of a patterning apparatus using a printing roller according to the related art.
As shown in FIG. 2, the patterning apparatus using the printing roller according to the related art is provided with a stage 110, a substrate 120 loaded onto the stage 110, a printing plate 130 loaded onto the stage 110 in parallel to the substrate 120, a printing unit 140 for printing the substrate 120 with a printing material 148 having a predetermined pattern of the printing plate 130, and a cleaning unit 150 for cleaning the printing plate 130.
The stage 110 supports the loaded substrate 120 with a substrate loading unit which is not shown. Disposed on the stage 110 is the substrate 120 and the printing plate 130 in parallel, wherein the printing plate 130 has the predetermined pattern of the printing material 148 to be printed on the substrate 120.
The printing plate 130 is positioned at a predetermined interval with the substrate 120 on the stage 110. The printing plate 130 has the predetermined pattern of the printing material 148 to be printed on the substrate 120.
The printing unit 140 is comprised of a printing roller 142, a blanket 144, and a nozzle 146. As the printing roller 142 is operated by a driving unit, the printing roller 142 is moved toward the printing plate 130 and the substrate 120 by rolling.
The blanket 144 is adhered to an outer surface of the printing roller 142, so as to print the printing material 148 patterned by the printing plate 130 on the substrate 120.
Through the nozzle 146, the printing material 148 is uniformly coated on the blanket 144. The printing material 148 is formed of ink such as photoresist.
The cleaning unit 150 is comprised of a spraying part and a drying part. The cleaning unit 150 cleans the printing material 148 left unused on the printing plate 130 after patterning the printing material 148.
A patterning method using the patterning apparatus of the related art will now be explained. While rolling the printing roller 142, the printing material 148 is supplied through the nozzle 146, and is coated on the surface of the blanket 144.
After positioning the printing roller 142 above the printing plate 130, the printing roller 142 is brought into contact with the predetermined pattern of the printing plate 130.
The printing material 148 coated on the blanket 144 is patterned by the printing plate 130. Since the adhesive strength between the printing plate 130 and the printing material 148 is larger than the adhesive strength between the blanket 144 and the printing material 148, the printing material 148 is printed on the predetermined pattern 132 of the printing plate 130.
After positioning the printing roller 142 above the substrate 120, the printing material 148 patterned on the blanket 144 is printed on the substrate 120 by rolling the printing roller 142. The printed material sticks to the substrate because an adhesive strength between the substrate 120 and the printing material 148 is larger than an adhesive strength between the blanket 144 and the printing material 148.
The printing unit containing the printing roller 142 is then positioned at an original state.
As shown in FIG. 4, after positioning the cleaning unit 150 above the printing plate 130, a cleaning solution is sprayed to the printing plate 130 by the spraying part. The cleaning solution may be formed of liquid chemical or ultra pure water DI. The spraying part of the cleaning unit 150 may have an additional brush. The drying part of the cleaning unit 150 dries the cleaning solution sprayed on the printing plate 130. After that, the cleaning unit 150 is positioned at an original state.
The patterning apparatus and method of the related art have disadvantages.
The patterning apparatus and method of the related art use a liquid chemical such as acetone in an open space. Using a liquid chemical requires additional cleanup. Thus, the cost and task time for performing a treatment to remove the environmental stink and the used liquid chemical is increased because additional cleanup is required.